My claim is that some of these optimizations on BFS/DFS style questions were never something most people could effortlessly solve in a few seconds. Which is how I took the claim of the OP.
If it was only the identification that was supposed to be seconds, with solutions taking time, that is one thing. But even binary search was infamous for not having a bug free solution for many many years. (Unless I took an urban legend too literally, of course.)
Not to mention, most solutions people give in seconds are at best a good starting position. Just go look at how a typical sort is actually implemented. Much more involved than what you would want someone to do in a few seconds.
I've literally seen folks that think someone should be able to write algorithms such as Knuth-Morris-Pratt in a standup interview. Which is just bonkers to me.
I've also grown annoyed with interviews that are effectively, "how would you design google maps today?" Which really just comes down to have I already done that. At the least, studied it fairly in depth. Worse, the answer is almost certainly not much different than how it was built.
